April 28 (Reuters) - Energy Transfer Partners LP, owner of gasoline retailer Sunoco Inc, said it would buy Susser Holdings Corp and create a separate retail company as it focuses on its core pipeline business.

Energy Transfer, which owns and operates about 35,000 miles of pipelines, said on Monday that it would buy Susser Holdings in a cash-and-stock deal valued at $1.8 billion.

Energy Transfer said it would combine its retail outlets and Susser’s convenience stores, including Stripes, and transfer it to a Susser unit to create a retail business after the deal closes in the third quarter.

“The drop down will allow us to exit retail business and focus on our core strength - that being moving hydrocarbons through our pipes,” Energy Transfer’s Chief Financial Officer Martin Salinas said on a conference call with analysts.

Demand for pipelines is growing in the United States as oil and gas producers struggle to move burgeoning shale supplies.

The Susser Holdings unit, Susser Petroleum Partners LP , distributes motor fuel to Stripes stores and other retailers. Energy Transfer gets the general partner interest in Susser Petroleum and 50.2 percent of its units under the deal.

Susser Holdings shareholders can opt to receive either $80.25 in cash, or 1.4506 Energy Transfer common units, or a combination of both, for each share held.